Response biases in auditory forebrain regions of female songbirds following exposure to sexually relevant variation in male song

In many species of songbirds, individual variation between the songs of com peting males is correlated with female behavioral preferences. The neural m echanisms of song based female preference in songbirds are not known. Worki ng with female European starlings (Sturnus vulgaris), we used immunocytoche mistry for ZENK protein to localize forebrain regions that respond to sexua lly relevant variation in conspecific male song. The number of ZENK-ir cell s in ventral caudo-medial neostriatum [NCMv] was significantly higher in fe males exposed to longer songs than in those exposed to shorter songs, where as variation in the total duration of song exposure yielded no significant differences in ZENK expression. ZENK expression in caudo-medial ventral hyp erstriatum [cmHV] was uniformly high in all subjects, and did not vary sign ificantly among the three groups. These results suggest that subregions of NCM in female starlings are tuned to variation in male song length, or to s ong features correlated therewith. Female starlings exhibit robust behavior al preferences for longer over shorter male songs (Gentner and Hulse; Anim Behav 59:443-458, 2000). Therefore, the results of this study strongly impl icate NCM in at least a portion of the perceptual processes underlying the complex natural behavior of female choice. (C) 2000 John Wiley & Sons, Inc.